Atom interferometers (AIs) have played an increasingly important role in state-of-the-art fundamental physics tests and quantum sensing scenarios with applications in a broad range from the test of Einstein’s equivalence principle [1]}, determination of the Newtonian gravitational constant [2]} to the precise measurement of gravity [3]}, gravity gradient [4]} and rotations [5]}. For a typical Raman-type AI, a compact and effective method for generating a pair of highly coherent Raman lasers is through electro-optic modulation, which exhibits low phase noise but suffers from the drift in modulation depth due to environmental disturbances [6]}, [7]}. This drift leads to instability of the power ratio of two Raman-lasers (PRTR), which will induce unwanted AC Stark shift [8]} in AIs and severely undermine the measuring precision in the case of short interrogation time or long-term operation. The probing and stabilization of this PRTR is therefore of practical importance to a high-precision and transportable AI.
